A number of vaccines have been developed for the control of diseases in fish, as illustrated for example, in U.S. Pat. Nos. 3,492,400 to Klontz and 3,862,313 to Fryer et al. In the past such vaccines have been administered by peritoneal injection or by incorporation in food or water. More recently vacuum infiltration (rapid pressure change) and hyperosmotic vaccine dips have been proposed. Peritoneal injections of large antigenic masses have been highly effective; however, when applied to large numbers of fish this method is cumbersome and costly. Incorporation of vaccine into the food or water is probably the most desirable system since it is relatively simple and economical. However, its effectiveness has been demonstrated in only a limited number of diseases. In addition the duration of protection by this method has been much shorter than that obtained by injection. The newer techniques of vacuum infiltration and hyperosmotic vaccine dips lend themselves to vaccination of small fish, but would be time consuming and costly when applied to larger fish. Unless the disease causing organism is constantly present to reinforce immunity, or if for any reason immunity is diminished, re-vaccination of larger fish with these techniques would be inefficient.
Spray vaccination will be especially useful where previously vaccinated fish are not constantly exposed to the disease causing agent. In this situation, unreinforced immunity may significantly decrease with time. For example, if salmon are vaccinated against V. anguillarum as fry, hatchery rearing periods as long as one year or more without natural contact with the target agent may lead to a reduction in protection. Before releasing the fish from the hatchery, the spray technique of this invention could be employed to revaccinate them, or possibly to supply a booster shot.
The present invention comprises an antigenic material useful for immunizing fish against disease and a spray method for administering the antigenic material to the fish.
Accordingly it is an object of the invention to provide an antigenic material for the immunization of fish against disease.
Another object of the invention is to provide a method for administering the antigenic material to fish efficiently and at low cost.
Another object is to provide a method for administering the antigenic material to the fish by means of a spray.
A further object of the invention is to provide a pressure spray method for immunizing fish employing antigenic material containing an absorbent.
Yet a further object of the invention is to employ an antigenic material containing an abrasive for administration to fish by means of a pressure spray.